Most gained, most lost, in one fight.

[ICB]

Douglas vs Tyson
JCC vs Meldrick Taylor 1
Lewis vs Ruddock
Jones vs Tarver 2
Curry vs Honeyghan

I'll think of some more later.

Good choices.
I especially like Curry v Honeyghan.
Of late Pavlik v Miranda. That really changed the Middleweight division.

Thanks heres few more.

Foreman vs Moorer
Tyson vs Spinks
Nelson vs Fenech 2